The present invention relates to a hydropneumatic suspension unit for wheeled vehicles, particularly off-road vehicles. Suspensions are known in which the wheel is carried by the body of a jack mounted slidably on a rod fixed to the chassis of the vehicle, and by a wishbone pivoted to the chassis and to the body of the jack, for example (MacPherson type suspension). With a suspension of this kind, and in fact with other known suspensions, the wheel associated with the suspension unit is also led, during its vertical oscillations, to turn on each side of this plane, so that the guidance of this wheel is inadequate. Furthermore, the size of the lower parts, particularly of the wishbone, limits ground clearance.